TWI641612B - Compound, light-emitting material and organic electroluminescence device - Google Patents

Abstract

The compound represented by D-A-D of the present invention is useful as a light-emitting material for use in an organic electroluminescence device or the like.

Description

Compound, luminescent material and organic light-emitting element

The present invention relates to a compound useful as a light-emitting material and an organic light-emitting element using the same.

Research on improving the luminous efficiency of organic light-emitting elements such as organic electroluminescent elements (organic EL elements) is prevailing. In particular, various methods are being conceived to newly develop and combine electron transport materials, hole transport materials, luminescent materials, and the like constituting the organic electroluminescence device, thereby improving luminous efficiency. Among them, studies on organic electroluminescent elements using compounds containing heteroaromatic rings have also been found, and several ideas have been proposed so far.

For example, Patent Document 1 discloses that a compound represented by the following formula [I] or formula [II] is used in an organic layer which is present between one of the counter electrode of the organic electroluminescence device. In the following formula, X ¹ and X ² represent N or CH, and Y ¹ and Y ² represent S, O, and NZ (Z is a hydrogen atom, an alkyl group, an aryl group, a cycloalkyl group, or a heterocyclic group), and R ¹ to R ⁴ represents a hydrogen atom, a halogen atom, a cyano group, a nitro group, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, a cycloalkyl group, an aryl group, a heterocyclic group, Amine, alkylamino, arylamine.

[Chemical 1]

Patent Document 1 discloses that the compound represented by the above formula [I] or formula [II] can be used as a fluorescent material in a light-emitting layer, or as a carrier in a hole injection layer or an electron injection layer. Transfer material. Further, in Patent Document 1, as a specific example of the compound represented by the above formula [I] or the formula [II], a compound having various structures is exemplified, and a compound A having the following structure is also exemplified.

Patent Document 2 discloses that in the organic electroluminescence device using a phosphorescent material, the compound of the above formula [I] or the formula [II] is used in the organic layer. Compound A is also described as an exemplary compound in Patent Document 2, and is used in the hole transport layer in the examples.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 10-340786

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2005-82703

Thus, the compound having the structure represented by the above formula [I] or the formula [II] has been proposed to be used in an organic electroluminescence device. However, these formulas include a wide range of compounds, and the structural examples described in Patent Document 1 or Patent Document 2 are also various. On the other hand, in Patent Document 1 or Patent Document 2, the compounds whose effects are specifically confirmed are only a few. In particular, in the above formula [I] or formula [II], as the kind of the substituent substituted on the aryl group in the case where R ¹ or R ² is an aryl group, only the one shown in the above compound A is listed. Diarylamine group and the like.

However, the organic electroluminescent element in which the above-mentioned compound A is used as a light-emitting material in the light-emitting layer is not high in luminous efficiency. Therefore, there is room for improvement in order to use the same series of compounds as luminescent materials. On the other hand, in Patent Document 1 or Patent Document 2, there is no description of the relationship between the luminous efficiency as a light-emitting material and the structure of a similar compound. Therefore, in Patent Document 1 or Patent Document 2, it is extremely difficult to accurately predict which property of a compound having a structure similar to the effect confirmed compound exhibits. Further, Patent Document 1 or Patent Document 2 specifically shows that the above-mentioned compound A having a structure has room for improvement in terms of luminous efficiency, but Patent Document 1 or Patent Document 2 regarding which structure can be used to improve luminous efficiency. There is no hint in it.

The inventors of the present invention have studied the problems of the prior art in order to provide a compound having high luminous efficiency. In addition, the general formula of a compound which is useful as a light-emitting material is derived, and the composition of an organic light-emitting element having high light-emitting efficiency has been developed.

The inventors of the present invention conducted intensive studies in order to achieve the above object, and as a result, a compound group having a specific structure was successfully synthesized, and these compound groups were found to have excellent properties as a light-emitting material. Further, it has been found that such a compound group is useful as a delayed fluorescent material, and it has been found that an organic light-emitting element having high luminous efficiency can be provided economically. The present inventors have provided the following invention as a means for solving the above problems based on these findings.

[1] A compound represented by the following formula (1), a formula (1) D-A-D

[In the general formula (1), A has the following general formula (2) to (5):

A divalent group of a structure represented by any one of the structures (wherein a hydrogen atom in the structure of the formulae (2) to (5) may be substituted with a substituent), and each of the two D groups independently represents a group selected from the group consisting of:

The structure of the structure in which the hydrogen atom in the structure may also be substituted by a substituent].

[2] The compound of [1], wherein A of the formula (1) has a structure represented by any one of the following formulae (6) to (9), [Chemical 5]

[In the general formulae (6) to (9), R ¹ to R ¹⁰ each independently represent a hydrogen atom or a substituent, and R ¹ and R ² , R ³ and R ⁴ , R ⁵ and R ⁶ , and R ⁷ and R ^{8 are} also They can be bonded to each other to form a ring structure].

[3] The compound of [1] or [2], wherein the two Ds of the formula (1) have the same structure.

[4] The compound of any one of [1] to [3], wherein D of the formula (1) has a structure represented by any one of the following formulas (10) to (12),

[In the general formulae (10) to (12), R ¹¹ to R ¹⁸ and R ²¹ to R ²⁵ each independently represent a hydrogen atom or a substituent, and R ¹¹ and R ¹² , R ¹² and R ¹³ , R ¹³ and R ¹⁴ , R ¹⁵ and R ¹⁶ , R ¹⁶ and R ¹⁷ , R ¹⁷ and R ¹⁸ , R ²¹ and R ²² , R ²² and R ²³ , R ²³ and R ²⁴ , R ²⁴ and R ²⁵ may be bonded to each other to form a ring. structure].

[5] The compound according to [4], wherein D has a structure represented by the formula (11).

[6] A luminescent material comprising the compound according to any one of [1] to [5].

[7] A delayed phosphor having a structure represented by the above formula (1).

[8] An organic light-emitting element characterized in that it has a light-emitting layer containing a light-emitting material of [6] on a substrate.

[9] The organic light-emitting element according to [8], which emits radiation delayed fluorescence.

[10] The organic light-emitting element according to [8] or [9], which is an organic electroluminescence element.

The compounds of the invention are useful as luminescent materials. Further, the compound of the present invention contains radiation delayed fluorescence. The use of the compound of the present invention as an organic light-emitting element of a light-emitting material can achieve higher luminous efficiency.

1‧‧‧Substrate

2‧‧‧Anode

3‧‧‧ hole injection layer

4‧‧‧ hole transport layer

5‧‧‧Lighting layer

6‧‧‧Electronic transport layer

7‧‧‧ cathode

Fig. 1 is a schematic cross-sectional view showing an example of a layer configuration of an organic electroluminescence device.

Figure 2 is a ¹ H NMR spectrum of Compound 1.

Figure 3 is a mass spectrum of Compound 1.

Figure 4 is a ¹ H NMR spectrum of Compound 3.

Figure 5 is a mass spectrum of Compound 3.

Figure 6 is a ¹ H NMR spectrum of Compound 4.

Figure 7 is a mass spectrum of Compound 4.

Fig. 8 is an emission spectrum of an organic photoluminescent device using Compound 1.

Figure 9 is a graph showing the transient decay curve of the organic photoluminescent device using Compound 1.

Fig. 10 is an emission spectrum of an organic photoluminescence element using Compound 3.

Figure 11 is a transient decay curve of an organic photoluminescent element using Compound 3.

Fig. 12 is an emission spectrum of an organic photoluminescence device using Compound 4.

Figure 13 is a graph showing the transient decay curve of an organic photoluminescent device using Compound 4.

Fig. 14 is an emission spectrum of an organic electroluminescence device using Compound 1.

Fig. 15 is a graph showing current density-external quantum efficiency characteristics of an organic electroluminescence device using Compound 1.

Fig. 16 is an emission spectrum of an organic electroluminescence device using Compound 3.

Fig. 17 is a graph showing current density-external quantum efficiency characteristics of an organic electroluminescence device using Compound 3.

Fig. 18 is an emission spectrum of an organic electroluminescence device using Compound 4.

Fig. 19 is a graph showing current density-external quantum efficiency characteristics of an organic electroluminescence device using Compound 4.

Hereinafter, the contents of the present invention will be described in detail. The description of the constituent elements described below may be carried out in accordance with a representative embodiment or a specific example of the present invention, but the present invention is not limited to such an embodiment or a specific example. In addition, the numerical range represented by "~" in this specification means the range which contains the numerical value of the [~~. Further, the isotopic type of the hydrogen atom present in the molecule of the compound used in the present invention is not particularly limited. For example, all of the hydrogen atoms in the molecule may be ¹ H, and some or all of them may be ² H (氘D).

[Compound represented by the formula (1)]

The compound of the present invention is characterized by having a structure represented by the following formula (1).

General formula (1) D-A-D

In the formula (1), A represents a divalent group having a structure represented by any one of the following formulas (2) to (5).

[Chemistry 7]

The hydrogen atom present in the above structure may also be substituted with a substituent. The number of substituents is not particularly limited, and the substituent may not be present. Further, when two or more substituents are present, the substituents may be the same or different from each other.

Examples of the substituent include a hydroxyl group, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkylthio group having 1 to 20 carbon atoms, and an aryl group having 6 to 40 carbon atoms. , a heteroaryl group having 3 to 40 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, a haloalkyl group having 1 to 10 carbon atoms, and a trialkylalkyl group having 3 to 20 carbon atoms. And a trialkylsulfanylalkyl group having 4 to 20 carbon atoms, a trialkylsulfonylalkylene group having 5 to 20 carbon atoms, a trialkyldecylalkylalkyne group having 5 to 20 carbon atoms, and the like. In these specific examples, those which may be further substituted with a substituent may also be substituted. More preferred substituents are substituted or unsubstituted alkyl groups having 1 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, substituted or unsubstituted aryl groups having 6 to 40 carbon atoms, and carbon number 3 ~40 substituted or unsubstituted heteroaryl. Further preferably, the substituent is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, and a carbon number of 6 to 15 A substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group having 3 to 12 carbon atoms.

The alkyl group may be linear, branched or cyclic, and more preferably has a carbon number of from 1 to 6. Specific examples include methyl, ethyl, propyl, butyl and t-butyl groups. , pentyl, hexyl, isopropyl. The alkoxy group may be any of a linear chain, a branched chain, and a cyclic group, and more preferably has a carbon number of 1 to 6. Specific examples thereof include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. , a third butoxy group, a pentyloxy group, a hexyloxy group, an isopropoxy group. The aryl group which may be used as a substituent may be a monocyclic ring or a condensed ring, and specific examples thereof include a phenyl group and a naphthyl group. The heteroaryl group may also be a monocyclic ring or a condensed ring, and specific examples thereof include a pyridyl group and a fluorene group. Base, pyrimidinyl, three Base, triazolyl, benzotriazolyl. The heteroaryl group may be a group bonded via a hetero atom or a group bonded via a carbon atom constituting the heteroaromatic ring.

The bonding position of D of the benzene ring bonded to the right end of the general formulae (2) to (5) may be either ortho, meta or para. Further, the bonding position of D of the benzene ring bonded to the left end of the general formulae (2) to (5) may be any of an ortho, meta or para position. Preferably, it is a meta or para position, and the best is the alignment.

A of the formula (1) is preferably a group having a structure represented by any one of the following formulas (6) to (9).

[化8]

In the general formulae (6) to (9), R ¹ to R ¹⁰ each independently represent a hydrogen atom or a substituent. R ¹ to R ¹⁰ may all be a hydrogen atom. Further, when two or more substituents are used, the substituents may be the same or different. For the description and preferred ranges of the substituents which may be taken from R ¹ to R ¹⁰ , reference may be made to the description of the substituents of the above formula (1) and the preferred ranges.

R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁶ and R ⁷ , and R ⁷ and R ⁸ may be bonded to each other to form a cyclic structure. The cyclic structure may be an aromatic ring or an aliphatic ring, or may be a hetero atom. Further, the cyclic structure may be a condensed ring of two or more rings. The hetero atom referred to herein is preferably selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom. Examples of the cyclic structure to be formed include a benzene ring, a naphthalene ring, a pyridine ring, and an anthracene. Ring, pyrimidine ring, pyridyl Ring, pyrrole ring, imidazole ring, pyrazole ring, triazole ring, imidazoline ring, Oxazole ring, different An azole ring, a thiazole ring, an isothiazole ring, a cyclohexadiene ring, a cyclohexene ring, a cyclopentene ring, a cycloheptatriene ring, a cycloheptadiene ring, a cycloheptene ring or the like.

Preferred examples of the structure represented by the general formulae (6) to (9) include those in which all of R ¹ to R ¹⁰ are hydrogen atoms. Further, a line symmetry structure in which R ¹ and R ⁸ , R ² and R ⁷ , R ³ and R ⁶ , R ⁴ and R ⁵ , and R ⁹ and R ¹⁰ are respectively the same may be mentioned.

Each of the two D groups of the formula (1) independently represents a group having a structure selected from the group consisting of the following.

The hydrogen atom present in the structure described in the above group may be substituted with a substituent. In particular, a hydrogen atom bonded to an atom constituting the ring skeleton may be substituted with a substituent. The number of substituents is not particularly limited, and the substituent may not be present. Also, there are more than two When the substituent is used, the substituents may be the same or different from each other.

Examples of the substituent which may be substituted with a hydrogen atom existing in the structure described in the above group include a hydroxyl group, a halogen atom, a cyano group, an alkyl group having 1 to 20 carbon atoms, and an alkoxy group having 1 to 20 carbon atoms. , an alkylthio group having 1 to 20 carbon atoms, an alkyl group-substituted amine group having 1 to 20 carbon atoms, an aryl group-substituted amine group having 12 to 40 carbon atoms, a fluorenyl group having 2 to 20 carbon atoms, and a carbon number of 6 to 40 Aryl group, heteroaryl group having 3 to 40 carbon atoms, substituted or unsubstituted carbazolyl group having 12 to 40 carbon atoms, alkenyl group having 2 to 10 carbon atoms, alkynyl group having 2 to 10 carbon atoms, carbon number 2 to 10 alkoxycarbonyl group, alkyl sulfonyl group having 1 to 10 carbon atoms, haloalkyl group having 1 to 10 carbon atoms, decylamino group, alkyl guanamine group having 2 to 10 carbon atoms, carbon number 3 a tert-alkylalkylene group of ~20, a trialkylsulfanylalkyl group having 4 to 20 carbon atoms, a trialkyldecylalkylalkenyl group having 5 to 20 carbon atoms, and a trialkyldecylalkylalkyne group having 5 to 20 carbon atoms. And nitro and the like. In these specific examples, those which may be further substituted with a substituent may also be substituted. More preferred substituents are a halogen atom, a cyano group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or a substituted or unsubstituted carbon number of 6 to 40. An aryl group, a substituted or unsubstituted heteroaryl group having 3 to 40 carbon atoms, a substituted or unsubstituted dialkylamino group having 1 to 10 carbon atoms, or a substituted or unsubstituted carbon number of 12 to 40 Substituted diarylamine group, substituted or unsubstituted carbazolyl group having 12 to 40 carbon atoms. Further preferred substituents are a fluorine atom, a chlorine atom, a cyano group, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, and a carbon number. a substituted or unsubstituted dialkylamino group of 1 to 10, a substituted or unsubstituted diarylamino group having 12 to 40 carbon atoms, a substituted or unsubstituted aryl group having 6 to 15 carbon atoms a substituted or unsubstituted heteroaryl group having 3 to 12 carbon atoms.

The hydrogen atoms on the adjacent ring skeleton atoms existing in the structure described in the above group are bonded to each other, and the substituents may be bonded to each other to form a cyclic structure. The cyclic structure may be an aromatic ring or an aliphatic ring, or may be a hetero atom. Further, the cyclic structure may be a condensed ring of two or more rings. Specific examples of the ring structure of the above general formulae (6) to (9) can be referred to for specific examples.

D of the formula (1) is preferably a group having a structure represented by any one of the following formulas (10) to (12).

In the general formulae (10) to (12), R ¹¹ to R ¹⁸ and R ²¹ to R ²⁵ each independently represent a hydrogen atom or a substituent. R ¹¹ and R ¹² , R ¹² and R ¹³ , R ¹³ and R ¹⁴ , R ¹⁵ and R ¹⁶ , R ¹⁶ and R ¹⁷ , R ¹⁷ and R ¹⁸ , R ²¹ and R ²² , R ²² and R ²³ , R ²³ R ²⁴ , R ²⁴ and R ²⁵ may be bonded to each other to form a cyclic structure.

The two Ds of the formula (1) may be the same or different, and preferably have the same structure. Further, the following is also preferable: A of the general formula (1) has a symmetrical structure, and two Ds are also the same, and the entire molecule adopts a symmetrical structure.

A general luminescent material has an A-D structure in which A functions as a receptor and D bonds which function as a donor. On the other hand, the compound represented by the formula (1) has a structure of D-A-D, and in the case of A which functions as a receptor, two bonds D function as a donor. When two or more Ds are bonded, it is generally feared that the functions as the donor are eliminated from each other, and there is a risk that the molecules do not function as a luminescent material and function effectively. However, it has been found that by separately selecting A and D and combining them according to the present invention, it is possible to provide a luminescent material having high luminous efficiency and excellent effects. The reason for this is considered to be that the expansion of HOMO and LUMO is controlled at a molecular level to satisfy the preferable conditions as a luminescent material.

The combination of A and D of the formula (1) can be arbitrarily selected, and for example, the following compounds are exemplified: A is a group having a structure represented by the formula (6), and D is a group having the formula (11) a compound represented by the structure; A is a group having a structure represented by the formula (7), and D is a compound having a structure represented by the formula (11); and A is a compound having the formula (8) a compound represented by a structure, and D is a compound having a structure represented by the general formula (11); A is a group having a structure represented by the general formula (9), and D is represented by the formula (11) a compound having a structure; A is a group having a structure represented by the formula (6), and D is a compound having a group represented by the formula (10); and A is represented by the formula (6) A compound of the structure, and D is a compound having a structure represented by the formula (12).

Specific examples of the compound represented by the formula (1) are exemplified below. However, the compound represented by the formula (1) which can be used in the present invention should not be construed as being limited by the specific examples.

The molecular weight of the compound represented by the formula (1) is preferably 1,500 or less, when it is intended to form and use an organic layer containing the compound represented by the formula (1) by a vapor deposition method. It is more preferably 1200 or less, further preferably 1,000 or less, and still more preferably 800 or less. The lower limit of the molecular weight is the molecular weight of the smallest compound represented by the formula (1).

The compound represented by the formula (1) can be formed into a film by a coating method regardless of the molecular weight. When a coating method is used, a compound having a relatively large molecular weight can be formed into a film.

It is also conceivable to apply the present invention to a compound containing a plurality of structures represented by the formula (1) in a molecule as a luminescent material.

For example, it is conceivable that a polymerizable group is present in the structure represented by the formula (1) in advance, and the polymerizable group is polymerized, and the polymer obtained thereby is used as a light-emitting material. Specifically, it is conceivable that a monomer containing a polymerizable functional group in any one of A or D of the formula (1) is subjected to homopolymerization or copolymerization with other monomers, thereby obtaining The polymer of the repeating unit is used as a luminescent material. Alternatively, it is also conceivable to react a compound having a structure represented by the general formula (1) with each other, thereby obtaining a dimer or Terpolymers, which are used as luminescent materials.

Examples of the polymer having a repeating unit having a structure represented by the formula (1) include a polymer having a structure represented by the following formula (13) or (14).

In the general formulae (13) and (14), Q represents a group containing a structure represented by the formula (1), and L ¹ and L ² represent a linking group. The carbon number of the linking group is preferably from 0 to 20, more preferably from 1 to 15, and still more preferably from 2 to 10. The linking group preferably has a structure represented by -X ¹¹ -L ¹¹ -. Here, X ¹¹ represents an oxygen atom or a sulfur atom, preferably an oxygen atom. L ¹¹ represents a linking group, preferably a substituted or unsubstituted alkylene group, or a substituted or unsubstituted extended aryl group, more preferably a substituted or unsubstituted alkylene group having a carbon number of 1 to 10. A phenyl group, or a substituted or unsubstituted phenyl group.

In the general formulae (13) and (14), R ¹⁰¹ , R ¹⁰² , R ¹⁰³ and R ¹⁰⁴ each independently represent a substituent. Preferably, it is a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 6 carbon atoms, a halogen atom, more preferably a carbon number of 1 to 3 Substituted alkyl group, unsubstituted alkoxy group having 1 to 3 carbon atoms, fluorine atom, chlorine atom, further preferably unsubstituted alkyl group having 1 to 3 carbon atoms, and having 1 to 3 carbon atoms Substituted alkoxy.

The linking group represented by L ¹ and L ² may be bonded to R ¹ to R ¹⁰ of the structure of the general formula (1) of Q, and R ¹ to R ¹⁰ of the structure of the general formula (6) to (9), 10) ~ (12) The structure of any of R ¹¹ ~ R ¹⁸ , R ²¹ ~ R ²⁸ . It is also possible to form a crosslinked structure or a network structure by connecting two or more linking groups to one Q.

Specific examples of the configuration of the repeating unit include the structures represented by the following formulas (15) to (18).

The polymer having the repeating unit containing the formulae (15) to (18) can be synthesized by introducing a hydroxyl group into any one of A or D of the structure of the formula (1) as a linker. The following compound is reacted to introduce a polymerizable group, and the polymerizable group is polymerized.

[化15]

The polymer having a structure represented by the formula (1) in the molecule may be a polymer composed only of a repeating unit having a structure represented by the formula (1), or may be a repeat having a structure other than the above. The polymer of the unit. Further, the repeating unit having the structure represented by the formula (1) contained in the polymer may be used alone or in combination of two or more. Examples of the repeating unit having no structure represented by the formula (1) include those derived from monomers used in usual copolymerization. For example, a repeating unit derived from a monomer having an ethylenically unsaturated bond such as ethylene or styrene may be mentioned.

[Synthesis method of compound represented by general formula (1)]

The compound represented by the formula (1) can be synthesized by combining known reactions. For example, the synthesis can be carried out according to the following procedure.

[化16] D-H+X-A-X → D-A-D

For the description of D and A in the above formula, the corresponding description of the general formula (1) can be referred to. X in the above formula represents a halogen atom, and examples thereof include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a chlorine atom, a bromine atom, and an iodine atom are preferred.

In the compound represented by the formula (1), for example, A is a structure represented by the formula (6). A compound in which D is a group having a structure represented by the formula (11) can be synthesized by the following scheme.

For the description of R ¹ to R ¹⁸ of the above formula, the corresponding description of the general formula (6) and the general formula (11) can be referred to. X of the above formula represents a halogen atom.

The reaction of the above two processes is to use a known reaction, and a known reaction condition can be appropriately selected and used. Regarding the details of the above reaction, a synthesis example described later can be referred to. Further, the compound represented by the formula (1) can also be synthesized by combining other known synthesis reactions.

[Organic light-emitting element]

The compound represented by the formula (1) of the present invention is useful as a light-emitting material of an organic light-emitting device. Therefore, the compound represented by the formula (1) of the present invention can be effectively used as a light-emitting material in the light-emitting layer of the organic light-emitting element. Among the compounds represented by the formula (1), a delayed fluorescent material (delayed phosphor) which emits delayed fluorescence is included. That is, the present invention also provides the invention of a delayed phosphor having the structure represented by the general formula (1), the invention of the compound represented by the general formula (1) as a delayed phosphor, and the use of the general formula (1) The invention is a method in which the compound represented by the method emits delayed fluorescence. An organic light-emitting element using such a compound as a light-emitting material has a feature of emitting delayed fluorescence and having high luminous efficiency. The principle of the organic electroluminescent device will be described as an example, as follows.

In the organic electroluminescence device, a carrier is injected from a positive electrode and a negative electrode to a light-emitting material, and a light-emitting material in an excited state is generated to emit light. In general, in the case of a carrier-injection type organic electroluminescence device, 25% of the generated excitons are excited to be excited singlet states, and the remaining 75% are excited to the excited triplet state. Therefore, in the case of utilizing the self-excited triplet light, that is, phosphorescence, the energy utilization efficiency is high. However, since the lifetime of the excited triplet state is long, in most cases, the energy is deactivated due to the saturation of the excited state or the interaction with the excitons of the excited triplet state, and generally the quantum yield of phosphorescence is not high. On the other hand, the delayed fluorescent material migrates to the excited triplet state by intersystem crossing or the like, and is radiated by the inverse intersystem crossing as the excited singlet state due to the triplet-triplet state elimination or the absorption of thermal energy. Fluorescent. Among the organic electroluminescence elements, heat-activated retardation fluorescent materials in which absorption by thermal energy is utilized are considered to be particularly useful. In the case where a delayed fluorescent material is used in an organic electroluminescence device, excitons that excite singlet states emit fluorescence as usual. On the other hand, the heat emitted by the exciton absorption device that excites the triplet state crosses the excitation singlet state and emits fluorescence. At this time, since it is a self-excited singlet luminescence, it is the same luminescence of the wavelength as the fluorescence, and the life of the generated light (luminous lifetime) is more common due to the crossover between the self-excited triplet state and the excited singlet state. Fluorescence or phosphorescence is longer and is observed as a fluorescence of these delays. It can be defined as delayed fluorescence. If using this heat The activated exciton shifting mechanism can increase the ratio of the compound which normally generates only 25% of the excited singlet state to 25% or more by absorption of thermal energy after the carrier is injected. That is to say, when a compound that emits strong fluorescence and delays fluorescence is used at a lower temperature of less than 100 ° C, the self-excited triplet state and the excited singlet crossover are sufficiently generated due to the heat of the device, and the radiation delay is emitted. Light, so it can dramatically improve luminous efficiency.

By using the compound represented by the formula (1) of the present invention as a light-emitting material of a light-emitting layer, it is possible to provide an organic organic photoluminescent element (organic PL element) or an organic electroluminescence element (organic EL element). Light-emitting element. In this case, the compound represented by the formula (1) of the present invention may also function as a so-called auxiliary dopant to have light emission of the other luminescent material contained in the auxiliary luminescent layer. That is, the compound represented by the formula (1) of the present invention contained in the light-emitting layer may have the lowest excited singlet energy level of the host material contained in the light-emitting layer and the lowest excitation single sheet of the other light-emitting material contained in the light-emitting layer. The lowest excited singlet energy level between the heavy energy levels.

The organic photoluminescent element has a structure in which at least a light-emitting layer is formed on a substrate. Further, the organic electroluminescence device has a structure in which at least an anode, a cathode, and an organic layer between the anode and the cathode are formed. The organic layer contains at least a light-emitting layer, and may be composed only of the light-emitting layer, or may have one or more organic layers in addition to the light-emitting layer. Examples of such other organic layers include a hole transport layer, a hole injection layer, an electron blocking layer, a hole blocking layer, an electron injection layer, an electron transport layer, and an exciton blocking layer. The hole transport layer may also be a hole injection transport layer having a hole injection function, and the electron transport layer may also be an electron injection transport layer having an electron injection function. A configuration of a specific organic electroluminescence device is shown in Fig. 1. In Fig. 1, 1 denotes a substrate, 2 denotes an anode, 3 denotes a hole injection layer, 4 denotes a hole transport layer, 5 denotes a light-emitting layer, 6 denotes an electron transport layer, and 7 denotes a cathode.

Hereinafter, each member and each layer of the organic electroluminescence device will be described. Further, the description of the substrate and the light-emitting layer corresponds to the substrate of the organic photoluminescent device and the light-emitting layer.

(substrate)

The organic electroluminescent device of the present invention is preferably supported by a substrate. The substrate is not particularly limited as long as it is conventionally used in an organic electroluminescence device, and for example, glass, transparent plastic, quartz, ruthenium or the like can be used.

(anode)

As the anode of the organic electroluminescence device, a metal having a large work function (4 eV or more), an alloy, a conductive compound, and a mixture thereof can be preferably used as the electrode material. Specific examples of such an electrode material include a metal such as Au, and a conductive transparent material such as CuI, indium tin oxide (ITO), SnO ₂ or ZnO. Further, a material which is amorphous and can be made into a transparent conductive film such as IDIXO (In ₂ O ₃ -ZnO) can also be used. Regarding the anode, the electrode materials can be formed into a thin film by vapor deposition or sputtering, and a pattern of a desired shape can be formed by photolithography, or when pattern precision is not required (100 μm or more). The pattern can be formed by masking a desired shape during vapor deposition or sputtering of the electrode material. Alternatively, in the case of using a material which can be applied as an organic conductive compound, a wet film formation method such as a printing method or a coating method can also be used. When the light is taken out from the anode, it is preferable that the transmittance is more than 10%, and the sheet resistance as the anode is preferably several hundred Ω/□ or less. Further, the film thickness is also selected depending on the material, and is usually in the range of 10 to 1000 nm, preferably 10 to 200 nm.

(cathode)

On the other hand, as the cathode, a metal having a small work function (4 eV or less) (referred to as an electron injecting metal), an alloy, a conductive compound, and a mixture thereof are used as the electrode material. Specific examples of such an electrode material include sodium, sodium-potassium alloy, magnesium, lithium, magnesium/copper mixture, magnesium/silver mixture, magnesium/aluminum mixture, magnesium/indium mixture, and aluminum/aluminum oxide (Al _{2 ).} O ₃ ) a mixture, indium, a lithium/aluminum mixture, a rare earth metal, or the like. Among these, in terms of electron injectability and durability against oxidation or the like, a mixture of an electron injecting metal and a second metal which is a larger and stable metal having a work function value is preferable, for example. Magnesium/silver mixture, magnesium/aluminum mixture, magnesium/indium mixture, aluminum/aluminum oxide (Al ₂ O ₃ ) mixture, lithium/aluminum mixture, aluminum, and the like. The cathode can be produced by forming the electrode material into a thin film by a method such as vapor deposition or sputtering. Further, the sheet resistance as the cathode is preferably several hundred Ω/□ or less, and the film thickness is selected in the range of usually 10 nm to 5 μm, preferably 50 to 200 nm. Further, in order to transmit the emitted light, if either the anode or the cathode of the organic electroluminescent element is transparent or translucent, the luminance of the light is improved and is good.

Further, by using the conductive transparent material exemplified in the description of the anode for the cathode, a transparent or translucent cathode can be produced, and by using the cathode, an element having permeability of both the anode and the cathode can be produced.

(lighting layer)

The light-emitting layer is a layer which generates an exciton light-emitting layer by recombining holes and electrons respectively injected from the anode and the cathode, and the light-emitting material can be used alone in the light-emitting layer, and preferably includes a light-emitting material and a host material. As the luminescent material, one type or two or more types selected from the group of compounds of the present invention represented by the formula (1) can be used. In order for the organic electroluminescent device and the organic photoluminescent device of the present invention to exhibit high luminous efficiency, it is important to block the singlet excitons and triplet excitons generated in the luminescent material in the luminescent material. Therefore, it is preferred to use a host material in addition to the luminescent material in the luminescent layer. As the host material, at least either of the excited singlet energy and the excited triplet energy can be used to have an organic compound having a higher value than the luminescent material of the present invention. As a result, the singlet excitons and triplet excitons generated in the luminescent material of the present invention can be enclosed in the molecules of the luminescent material of the present invention, and the luminescent efficiency can be sufficiently extracted. However, even if the singlet excitons and the triplet excitons are not sufficiently blocked, a higher luminous efficiency can be obtained, so that it is not particularly limited as long as it is a host material capable of achieving high luminous efficiency. In the present invention. In the organic light-emitting device or the organic electroluminescence device of the present invention, the light-emitting device is produced by the light-emitting material of the present invention contained in the light-emitting layer. The luminescence includes both fluorescent luminescence and delayed luminescence. However, it is also possible for some or part of the luminescence to have luminescence from the host material.

In the case of using a host material, the compound of the present invention as a luminescent material is The amount contained in the light-emitting layer is preferably 0.1% by weight or more, more preferably 1% by weight or more, further preferably 50% by weight or less, more preferably 20% by weight or less, still more preferably 10% by weight or less.

As the host material in the light-emitting layer, an organic compound having a hole transporting ability and an electron-transporting ability, and capable of preventing long-wavelength of light emission and further having a high glass transition temperature is preferable.

(injection layer)

The injection layer means a layer provided between the electrode and the organic layer in order to lower the driving voltage or increase the luminance of the light, and has a hole injection layer and an electron injection layer, and may exist between the anode and the light-emitting layer or the hole transport layer. And between the cathode and the light emitting layer or the electron transport layer. The injection layer can be set as needed.

(barrier layer)

The barrier layer is a layer that blocks charges (electrons or holes) and/or excitons that are present in the light-emitting layer from diffusing outside the light-emitting layer. The electron blocking layer may be disposed between the light emitting layer and the hole transport layer to block electrons from passing through the light emitting layer in the direction of the hole transport layer. Similarly, the hole blocking layer may be disposed between the light emitting layer and the electron transport layer, and the blocking hole passes through the light emitting layer toward the electron transport layer. The barrier layer can in turn be used to block the diffusion of excitons to the outside of the luminescent layer. That is, the electron blocking layer and the hole blocking layer may each function as an exciton blocking layer. The electron blocking layer or exciton blocking layer described in the present specification is used in the sense of including a layer having a function of an electron blocking layer and an exciton blocking layer in one layer.

(hole blocking layer)

The so-called hole blocking layer has a function of an electron transport layer in a broad sense. The hole blocking layer has the function of transmitting electrons on one side and blocking the holes to the electron transport layer, thereby increasing the probability of recombination of electrons and holes in the light-emitting layer. As the material of the hole blocking layer, the material of the electron transport layer described below may be used as needed.

(electronic barrier layer)

The so-called electron blocking layer has a function of transmitting holes in a broad sense. The electron blocking layer has a function of transmitting a hole on one side and blocking electrons from reaching the hole transport layer, thereby increasing the probability of recombination of electrons and holes in the light-emitting layer.

(exciton blocking layer)

The exciton blocking layer refers to a layer for blocking the diffusion of excitons generated by recombination of holes and electrons into the charge transport layer in the light-emitting layer, and the excitons can be efficiently enclosed by the insertion of the layer. Within the layer, the luminous efficiency of the component can be improved. The exciton blocking layer may be inserted adjacent to the light emitting layer adjacent to either the anode side or the cathode side, or may be simultaneously inserted to both sides. That is, in the case where the exciton blocking layer is provided on the anode side, the layer may be inserted between the hole transport layer and the light emitting layer adjacent to the light emitting layer, and in the case of being inserted to the cathode side, the light emitting layer and the cathode may be used. The layer is inserted between adjacent to the light-emitting layer. Further, between the anode and the exciton blocking layer adjacent to the anode side of the light-emitting layer, a hole injection layer or an electron blocking layer may be provided between the cathode and the exciton blocking layer adjacent to the cathode side of the light-emitting layer. There are an electron injecting layer, an electron transporting layer, a hole blocking layer, and the like. In the case of arranging the barrier layer, it is preferred that at least one of the excited singlet energy and the excited triplet energy of the material used as the barrier layer is higher than the excited singlet energy and the excited triplet energy of the luminescent material.

(hole transport layer)

The hole transport layer includes a hole transport material having a function of transmitting a hole, and the hole transport layer may be provided with a single layer or a plurality of layers.

The hole transporting material may be any one of an organic substance and an inorganic substance, and may be any one of an injection or a transmission of a hole and a barrier property of an electron. As a known hole transporting material which can be used, for example, a triazole derivative can be cited. Diazole derivatives, imidazole derivatives, carbazole derivatives, carbazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamines Derivatives, amine-substituted chalcone derivatives, An azole derivative, a styryl hydrazine derivative, an anthrone derivative, an anthracene derivative, a stilbene derivative, a decazane derivative, an aniline-based copolymer, or a conductive polymer oligomer, especially a thiophene As the oligomer or the like, a porphyrin compound, an aromatic tertiary amine compound, and a styrylamine compound are preferably used, and an aromatic tertiary amine compound is more preferably used.

(electronic transport layer)

The electron transport layer includes a material having a function of transmitting electrons, and the electron transport layer may be provided with a single layer or a plurality of layers.

As the electron transporting material (which also serves as a hole blocking material), it is only required to have a function of transferring electrons injected from the cathode to the light emitting layer. Examples of the electron transporting layer which can be used include a nitro-substituted anthracene derivative, a biphenyl hydrazine derivative, a thiopyran dioxide derivative, a carbodiimide, a fluorenylene methane derivative, and a quinodimethane. And anthrone derivatives, Diazole derivatives and the like. Further, the above Among the oxadiazole derivatives, a thiadiazole derivative in which an oxygen atom of a diazole ring is substituted with a sulfur atom, and a quinine known as a pull electron group Quinone ring The porphyrin derivative can also be used as an electron transporting material. Further, a polymer material in which the materials are introduced into the polymer chain or the materials are used as a main chain of the polymer may be used.

When the organic electroluminescent device is produced, not only the compound represented by the formula (1) but also the layer other than the light-emitting layer can be used. In this case, the compound represented by the formula (1) used in the light-emitting layer may be the same as or different from the compound represented by the formula (1) used in the layer other than the light-emitting layer. For example, a compound represented by the formula (1) can also be used in the above injection layer, barrier layer, hole barrier layer, electron blocking layer, exciton blocking layer, hole transport layer, electron transport layer and the like. The film forming method of the layers is not particularly limited, and it may be produced by any of a dry process or a wet process.

Hereinafter, preferred materials which can be used in the organic electroluminescence element are specifically exemplified. However, materials which can be used in the present invention are not limited by the following exemplified compounds. Further, even a compound exemplified as a material having a specific function can be used as a material having other functions. Further, in the structural formulae of the following exemplified compounds, R, R' and R ₁ to R ₁₀ each independently represent a hydrogen atom or a substituent. Further, in the structural formulae of the following exemplified compounds, R and R ₁ to R ₁₀ each independently represent a hydrogen atom or a substituent. n represents an integer from 3 to 5.

First, preferred compounds which can also be used as a host material for the light-emitting layer are listed.

[Chem. 21]

[化22]

Next, an example of a preferred compound which can be used as a hole injecting material is listed.

[化23]

Next, examples of preferred compounds which can be used as a hole transporting material are listed.

[Chem. 24]

[化25]

[Chem. 26]

[化27]

[化28]

[化29]

Next, examples of preferred compounds which can be used as electron blocking materials are listed.

Next, an example of a preferred compound which can be used as a barrier material for a hole is listed.

Next, examples of preferred compounds which can be used as electron transport materials are listed.

[化33]

[化34]

Next, examples of preferred compounds which can be used as electron injecting materials are listed.

Examples of preferred compounds are listed as further addable materials. For example, it is conceivable to add as a stable material or the like.

[化36]

The organic electroluminescent element produced by the above method emits light by applying an electric field between the anode and the cathode of the obtained element. At this time, if the light is obtained by exciting the singlet energy, the light of the wavelength corresponding to the energy level is confirmed as the fluorescent light emission and the delayed fluorescent light emission. Further, in the case of light emission obtained by exciting the triplet energy, the wavelength corresponding to the energy level is confirmed as phosphorescence. Generally, the fluorescent lifetime of fluorescent light is shorter than that of delayed fluorescent light, so the luminous lifetime can be distinguished by fluorescent and delayed fluorescent.

On the other hand, in the case of phosphorescence, in the case of a usual organic compound such as the compound of the present invention, the excited triplet energy is unstable and converted into heat, and the life is short and immediately deactivated, so that it is almost impossible to observe at room temperature. To. In order to measure the excited triplet energy of a typical organic compound, it can be measured by observing the luminescence under extremely low temperature conditions.

The organic electroluminescence device of the present invention can be applied to any of a single element, an element including a structure arranged in an array, and a structure in which an anode and a cathode are arranged in an X-Y matrix. According to the invention, by including the compound represented by the formula (1) in the light-emitting layer, an organic light-emitting device in which the light-emitting efficiency is greatly improved can be obtained. The organic light-emitting element such as the organic electroluminescence device of the present invention can be further applied to various applications. For example, an organic electroluminescence display device can be manufactured using the organic electroluminescence device of the present invention, with regard to the detailed case, You can refer to the "Organic EL Display" (Ohm), which is co-authored by Jing Shi, Anda Chiba, and Murata. Further, in particular, the organic electroluminescence device of the present invention can also be applied to an organic electroluminescence illumination or backlight device which is in great demand.

[Examples]

The features of the present invention will be further specifically described below by way of Synthesis Examples and Examples. The materials, processing contents, processing procedures, and the like shown below may be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the invention should not be construed as limited by the specific examples shown below.

(Synthesis Example 1) Synthesis of Compound 1

2.0 g (8.2 mmol) of 2,5-diaminobenzene-1,4-dithiol dihydrochloride and 3.8 g (18.8 mmol) of 4-bromobenzoic acid were placed in a 100 ml two-necked flask. 30 ml of polyphosphoric acid was added to the reactor, and the mixture was heated at 100 ° C for 30 hours and stirred. After the reaction, the heating was stopped, and the reaction liquid was cooled to room temperature, and then the reaction mixture was poured into a mixed solution of 300 ml of water and 300 ml of chloroform. The organic phase was separated from the aqueous phase by a separating funnel, and the organic phase was dried and concentrated, and then 100 ml of methanol was added to allow the solid matter to be analyzed. The precipitate was subjected to suction filtration and dried to obtain 3.8 g (yield 93%) of dibromo as a reaction intermediate as a yellow powder.

0.71 g (1.4 mmol) of one part of the obtained dibromide and brown 0.65 g (3.5 mmol) and potassium carbonate 0.59 g (4.3 mmol) were placed in a 50 ml two-necked flask which was replaced with nitrogen. A mixture of 0.032 g (0.14 mmol) of palladium acetate and 0.029 g (0.14 mmol) of tri-t-butylphosphine dissolved in 10 ml of dehydrated toluene degassed by high-purity nitrogen gas was added dropwise to the reactor. The solution was heated at 80 ° C for 24 hours under a nitrogen atmosphere and stirred. After completion of the reaction, 300 ml of water and 300 ml of chloroform were added to the reaction mixture, and the organic phase was separated from the aqueous phase. After concentrating the organic phase, 100 ml of methanol was added, and ultrasonic irradiation was performed for 10 minutes to analyze the solid matter. After the precipitated solid matter was subjected to suction filtration and dried, the obtained powder was sublimed and purified at 370 ° C to obtain 0.12 g of a yellow powder of Compound 1 (yield 12%). ¹ H-NMR spectrum (CDCl ₃ , 500 MHz) is shown in Fig. 2, and mass spectrum is shown in Fig. 3.

(Synthesis Example 2) Synthesis of Compound 3

1.5 g (7.0 mmol) of 4,6-diaminohydroquinone dihydrochloride, 3.3 g (16.4 mmol) of 4-bromobenzoic acid, and 30 ml of polyphosphoric acid were placed in a 100 ml two-necked flask, and heated at 100 ° C. Stirring was carried out for 72 hours. After the heating was stopped and the mixture was cooled to room temperature, the reactant was poured into a mixed solution of 300 ml of water and 300 ml of chloroform, and then the organic phase was separated from the aqueous phase by a separating funnel. After the organic phase is dried and concentrated, 100 ml of methanol is added to analyze the solid matter. Out. The solid content component was filtered and dried to obtain 2.7 g (yield: 79%) of a purple powder as a dibromo compound as a reaction intermediate.

One part of the obtained dibromide, 0.70 g (1.5 mmol) and brown 0.60 g (3.3 mmol) and 1.23 g (9.9 mmol) of potassium carbonate were placed in a 200 ml two-necked flask which was replaced with nitrogen. A mixture of 0.033 g (0.15 mmol) of palladium acetate and 0.030 g (0.15 mmol) of tri-tert-butylphosphine dissolved in 50 ml of dehydrated toluene subjected to degassing treatment with high-purity nitrogen gas was added dropwise to the reactor. The solution was heated at 80 ° C for 48 hours under a nitrogen atmosphere and stirred.

After completion of the reaction, a mixed solution of 300 ml of water and 300 ml of chloroform was added to the reaction mixture, and the organic phase was separated from the aqueous phase by a separating funnel. After the organic phase was concentrated and dried, 100 ml of methanol was added, and ultrasonic irradiation was performed for 10 minutes to analyze the solid matter. The precipitated solid matter was filtered, dried, and the obtained powder was purified by sublimation at 350 ° C to obtain 0.57 g of Compound 3 (yield 57%) as yellow needle crystals. The ¹ H-NMR spectrum (CDCl ₃ , 500 MHz) is shown in Fig. 4, and the mass spectrum is shown in Fig. 5.

(Synthesis Example 3) Synthesis of Compound 4

1.5 g (7.0 mmol) of 4,6-diaminoresorcinol dihydrochloride, 3.3 g (16.4 mmol) of 4-bromobenzoic acid, and 20 ml of polyphosphoric acid were placed in a 100 ml two-necked flask, and heated at 100 ° C. Stir for 24 hours. After the heating was stopped and the mixture was cooled to room temperature, the reactant was poured into a mixed solution of 300 ml of water and 300 ml of chloroform, and then the organic phase was separated from the aqueous phase by a separating funnel. After the organic phase was dried and concentrated, 100 ml of methanol was added to analyze the solid matter. This solid component was filtered and dried to obtain 3.0 g (yield 88%) of a white powder as a dibromo compound as a reaction intermediate.

One part of the obtained dibromide, 0.70 g (1.5 mmol) and brown 0.60 g (3.3 mmol) and 1.23 g (9.9 mmol) of potassium carbonate were placed in a 200 ml two-necked flask which was replaced with nitrogen. A mixture of 0.033 g (0.15 mmol) of palladium acetate and 0.030 g (0.15 mmol) of tri-tert-butylphosphine dissolved in 50 ml of dehydrated toluene subjected to degassing treatment with high-purity nitrogen gas was added dropwise to the reactor. The solution was heated at 80 ° C for 48 hours under a nitrogen atmosphere and stirred.

After completion of the reaction, a mixed solution of 300 ml of water and 300 ml of chloroform was added to the reaction mixture, and the organic phase was separated from the aqueous phase by a separating funnel. After the organic phase was concentrated and dried, 100 ml of methanol was added, and ultrasonic irradiation was performed for 10 minutes to analyze the solid matter. The precipitated solid matter was filtered, dried, and the obtained powder was purified by sublimation at 350 ° C to obtain 0.28 g of Compound 4 (yield 28%) as yellow needle crystals. The ¹ H-NMR spectrum (CDCl ₃ , 500 MHz) is shown in Fig. 6, and the mass spectrum is shown in Fig. 7.

(Example 1) Production and evaluation of organic photoluminescent device (film)

The compound 1 and CBP were vapor-deposited from different evaporation sources under vacuum conditions of 5.0×10 ⁻⁴ Pa on a substrate, and the concentration of the compound 1 was formed to a thickness of 0.3 nm/s and 100 nm. 6.0% by weight of the film was made into an organic photoluminescent element.

For the organic photoluminescent device to be fabricated, a semiconductor parameter analyzer (manufactured by Agilent Technologies: E5273A), an optical power meter measuring device (manufactured by Newport: 1930C), an optical spectroscope (manufactured by Ocean Optics: USB2000), and a fast The measurement was carried out by a camera (manufactured by Hamamatsu Photonics Co., Ltd.: Model C4334). The luminescence spectrum obtained by excitation light at 330 nm is shown in Fig. 8, and the transient decay curve is shown in Fig. 9. The The transient decay curve is a measurement result of the luminescence lifetime obtained by irradiating the compound with excitation light and measuring the gradual deactivation of the luminescence intensity. In the case of one component luminescence (fluorescent or phosphorescent), the luminescence intensity is attenuated by a single exponential function. It means that the vertical axis of the graph is a semi-log (semilog) and is linearly attenuated. In the transient decay curve of Compound 1, such a linear component (fluorescence) was observed at the beginning of the observation, but a component deviating from the linearity occurred after a few μ second. This is a luminescence of the delayed component, and the signal added to the initial component becomes a easing curve to the long-term side. By measuring the luminescence lifetime in this manner, it was confirmed that the compound 1 is an illuminant containing a retardation component in addition to the fluorescent component.

The photoluminescence quantum efficiency was measured at 300 K, and as a result, it was 60% in the atmosphere and 78% in a nitrogen atmosphere.

An organic photoluminescent element was produced by the same method using Compound 3 instead of Compound 1. The luminescence spectrum obtained from the excitation light of 330 nm is shown in Fig. 10, and the transient attenuation curve is shown in Fig. 11. The photoluminescence quantum efficiency was measured at 300 K, and as a result, it was 21% in the atmosphere and 60% in a nitrogen atmosphere.

An organic photoluminescent element was produced by the same method using Compound 4 instead of Compound 1. The luminescence spectrum obtained from the excitation light at 330 nm is shown in Fig. 12, and the transient attenuation curve is shown in Fig. 13. The photoluminescence quantum efficiency was measured at 300 K, and as a result, it was 84% in the atmosphere and 98% in the nitrogen atmosphere.

(Example 2) Production and evaluation of organic electroluminescent elements

On each of the glass substrates on which an anode containing indium tin oxide (ITO) having a film thickness of 100 nm was formed, each film was laminated by a vacuum deposition method at a degree of vacuum of 5.0 × 10 ^-4 Pa. First, α-NPD having a thickness of 35 nm was formed on ITO. Next, Compound 1 and CBP were co-evaporated from different vapor deposition sources to form a layer having a thickness of 15 nm to prepare a light-emitting layer. At this time, the concentration of the compound 1 was set to 6.0% by weight. Next, TPBi having a thickness of 65 nm was formed, and lithium fluoride (LiF) of 0.8 nm was vacuum-deposited, and then aluminum (Al) was vapor-deposited to a thickness of 80 nm to form a cathode, thereby preparing an organic electroluminescence device.

The manufactured organic electroluminescence device was measured using a semiconductor parameter analyzer (manufactured by Agilent Technologies, Inc.: E5273A), an optical power meter measuring device (manufactured by Newport Corporation: 1930C), and an optical spectroscope (manufactured by Ocaen Optics Co., Ltd.: USB2000). The luminescence spectrum is shown in Fig. 14, and the current density-external quantum efficiency characteristics are shown in Fig. 15. The organic electroluminescent device using Compound 1 as a light-emitting material achieved a high external quantum efficiency of 13.5%. The photoluminescence quantum efficiency of using Compound 1 as a light-emitting material was 78%, and the singlet exciton generation probability was calculated to be 87% (the light extraction efficiency was set to 20%, and the recombination probability was set to 100%). .

When an organic electroluminescence device having an ideal balance is attempted by using a fluorescent material having a luminescence quantum efficiency of 100%, if the light extraction efficiency is 20 to 30%, the external quantum efficiency of the luminescence is 5 to 7.5%. . This value is generally considered to be the theoretical limit of the external quantum efficiency of an organic electroluminescent element using a fluorescent material. The organic electroluminescent device of the present invention using Compound 1 is extremely excellent in achieving a higher external quantum efficiency (13.5%) exceeding a theoretical limit value.

An organic electroluminescence device was produced by the same method using Compound 3 instead of Compound 1, and mCBP instead of CBP. The luminescence spectrum is shown in Fig. 16, and the current density-external quantum efficiency characteristics are shown in Fig. 17. The organic electroluminescent device using Compound 3 as a light-emitting material achieved a high external quantum efficiency of 13.3%. The photoluminescence quantum efficiency of using Compound 3 as a luminescent material was 81%, and the singlet exciton generation probability was calculated to be 82% (the light extraction efficiency was set to 20%, and the recombination probability was set to 100%). .

An organic electroluminescence device was produced by the same method using Compound 4 instead of Compound 1, and mCBP instead of CBP. The luminescence spectrum is shown in Fig. 18, and the current density-external quantum efficiency characteristics are shown in Fig. 19. The organic electroluminescent element using Compound 4 as a light-emitting material achieved a high external quantum efficiency of 16.4%. The photoluminescence quantum efficiency of using Compound 4 as a light-emitting material was 98%, whereby the singlet exciton generation probability was calculated to be 84% (the light extraction efficiency was set to 20%, and the recombination probability was set to 100%). .

The compound A having the above structure and the compound 1, the compound 3, and the compound 4 of the examples were subjected to a density functional method (TD-DFT (PBE1PBE/6-31G)) to calculate the difference between the singlet energy and the triplet energy of the molecule ( ⊿E _ST ), the results are shown in Table 1. As a result, Compound A had a larger ⊿E _ST value than the compound of the Example, indicating that the luminescence ability was low.

[Industrial availability]

The compounds of the invention are useful as luminescent materials. Therefore, the compound of the present invention can be effectively used as a light-emitting material for an organic light-emitting element such as an organic electroluminescence device. The compound of the present invention also includes radiation-delayed fluorescence, so that it can also provide high luminous efficiency. Machine lighting element. Therefore, the industrial availability of the present invention is high.

Claims (10)

A compound represented by the following formula (1), a formula (1) DAD [in the formula (1), A has the following formula (2) to (5): Any of the structures represented by the structure (wherein the hydrogen atoms in the structures of the general formulae (2) to (5) may also pass through a hydroxyl group, a halogen atom, an alkyl group having 1 to 20 carbon atoms, and an alkoxy group having 1 to 20 carbon atoms. Base, alkylthio group having 1 to 20 carbon atoms, aryl group having 6 to 40 carbon atoms, heteroaryl group having 3 to 40 carbon atoms, alkenyl group having 2 to 10 carbon atoms, alkynyl group having 2 to 10 carbon atoms, carbon a haloalkyl group having 1 to 10, a trialkylsulfanyl group having 3 to 20 carbon atoms, a trialkyldecylalkyl group having 4 to 20 carbon atoms, a trialkyldecylalkylene group having 5 to 20 carbon atoms, or a divalent group having a carbon number of 5 to 20, a trialkylsulfonylalkynyl group substituted, and 2 D's each independently represent a group selected from the group consisting of: The structure in which the hydrogen atom in the structure may also pass through a hydroxyl group, a halogen atom, a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and an alkylthio group having 1 to 20 carbon atoms. , an alkyl substituted amine having 1 to 20 carbon atoms, an aryl substituted amine having 12 to 40 carbon atoms, a fluorenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 40 carbon atoms, and a carbon number of 3 to 40 Aryl group, carbazolyl group having 12 to 40 carbon atoms, alkenyl group having 2 to 10 carbon atoms, alkynyl group having 2 to 10 carbon atoms, alkoxycarbonyl group having 2 to 10 carbon atoms, alkyl group having 1 to 10 carbon atoms Sulfonyl group, haloalkyl group having 1 to 10 carbon atoms, decylamino group, alkyl guanamine group having 2 to 10 carbon atoms, trialkylsulfonyl group having 3 to 20 carbon atoms, and tridecane having 4 to 20 carbon atoms a group based on an alkylalkyl group, a trialkylsulfonylalkenyl group having 5 to 20 carbon atoms, a trialkylsulfanylalkynyl group having 5 to 20 carbon atoms or a nitro group). A compound represented by the following formula (1), wherein the formula (1) is a compound represented by any one of the following formulae (6) to (9). : [In the general formulae (6) to (9), R ¹ to R ¹⁰ each independently represent a hydrogen atom, a hydroxyl group, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a carbon number of 1; ~20 alkylthio group, carbon number 6 to 40 aryl group, carbon number 3 to 40 heteroaryl group, carbon number 2 to 10 alkenyl group, carbon number 2 to 10 alkynyl group, carbon number 1 to 10 Haloalkyl group, trialkylsulfonyl group having 3 to 20 carbon atoms, trialkylsulfonylalkyl group having 4 to 20 carbon atoms, trialkyldecylalkylene group having 5 to 20 carbon atoms, or carbon number 5 to 20 a trialkylsulfonylalkynyl group, R ¹ and R ² , R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁷ and R ⁸ may be bonded to each other to form a benzene ring, a naphthalene ring or a cyclohexadiene ring. a divalent group of a cyclohexene ring, a cyclopentene ring, a cycloheptatriene ring, a cycloheptadiene ring, or a cycloheptene ring, wherein each of D is independently represented by the group selected from the group consisting of: The structure in which the hydrogen atom in the structure may also pass through a hydroxyl group, a halogen atom, a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and an alkylthio group having 1 to 20 carbon atoms. , an alkyl substituted amine having 1 to 20 carbon atoms, an aryl substituted amine having 12 to 40 carbon atoms, a fluorenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 40 carbon atoms, and a carbon number of 3 to 40 Aryl group, carbazolyl group having 12 to 40 carbon atoms, alkenyl group having 2 to 10 carbon atoms, alkynyl group having 2 to 10 carbon atoms, alkoxycarbonyl group having 2 to 10 carbon atoms, alkyl group having 1 to 10 carbon atoms Sulfonyl group, haloalkyl group having 1 to 10 carbon atoms, decylamino group, alkyl guanamine group having 2 to 10 carbon atoms, trialkylsulfonyl group having 3 to 20 carbon atoms, and tridecane having 4 to 20 carbon atoms a group based on an alkylalkyl group, a trialkylsulfonylalkenyl group having 5 to 20 carbon atoms, a trialkylsulfanylalkynyl group having 5 to 20 carbon atoms or a nitro group). The compound of claim 1, wherein the two Ds of the formula (1) have the same structure. A compound represented by the following formula (1), a formula (1) DAD [in the formula (1), A has the following formula (2) to (5): Any of the structures represented by the structure (wherein the hydrogen atoms in the structures of the general formulae (2) to (5) may also pass through a hydroxyl group, a halogen atom, an alkyl group having 1 to 20 carbon atoms, and an alkoxy group having 1 to 20 carbon atoms. Base, alkylthio group having 1 to 20 carbon atoms, aryl group having 6 to 40 carbon atoms, heteroaryl group having 3 to 40 carbon atoms, alkenyl group having 2 to 10 carbon atoms, alkynyl group having 2 to 10 carbon atoms, carbon a haloalkyl group having 1 to 10, a trialkylsulfanyl group having 3 to 20 carbon atoms, a trialkyldecylalkyl group having 4 to 20 carbon atoms, a trialkyldecylalkylene group having 5 to 20 carbon atoms, or a divalent group having a C 5 to 20-tertylalkylalkylalkynyl group substituted, and each of the two Ds independently represents a structure represented by any one of the following formulas (10) to (12). [In the general formulae (10) to (12), R ¹¹ to R ¹⁸ and R ²¹ to R ²⁵ each independently represent a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 20 carbon atoms, and a carbon number of 1 to 20; Alkoxy group, alkyl 1 thiol group having 1 to 20 carbon atoms, alkyl substituted amine group having 1 to 20 carbon atoms, aryl substituted amine group having 12 to 40 carbon atoms, fluorenyl group having 2 to 20 carbon atoms, carbon number 6 to 40 aryl groups, carbon number 3 to 40 heteroaryl groups, carbon number 12 to 40 carbazolyl groups, carbon number 2 to 10 alkenyl groups, carbon number 2 to 10 alkynyl groups, carbon number 2 to 10 Alkoxycarbonyl group, alkylsulfonyl group having 1 to 10 carbon atoms, haloalkyl group having 1 to 10 carbon atoms, decylamino group, alkyl guanamine group having 2 to 10 carbon atoms, carbon number 3 to 20 Trialkyldecylalkyl, trialkylsulfonylalkyl group having 4 to 20 carbon atoms, trialkylsulfonylalkenyl group having 5 to 20 carbon atoms, trialkylsulfonylalkynyl group having 5 to 20 carbon atoms or nitro group R ¹¹ and R ¹² , R ¹² and R ¹³ , R ¹³ and R ¹⁴ , R ¹⁵ and R ¹⁶ , R ¹⁶ and R ¹⁷ , R ¹⁷ and R ¹⁸ , R ²¹ and R ²² , R ²² and R ²³ , R ²³ and R ²⁴ , R ²⁴ and R ²⁵ may also be bonded to each other to form a benzene ring, a naphthalene ring, a cyclohexadiene ring, a cyclohexene ring, a cyclopentene ring, a cycloheptatriene ring or a cycloheptadiene ring. Or cycloheptene ring]. The compound of claim 4, wherein D has the structure represented by the formula (11). Use of a compound according to any one of claims 1 to 5 as a luminescent material. A compound represented by the following formula (1) is used as a delayed phosphor, and the formula (1) DAD [in the formula (1), A has the following formula (2) to (5): [Chemical 5] Any of the structures represented by the structure (wherein the hydrogen atoms in the structures of the general formulae (2) to (5) may also pass through a hydroxyl group, a halogen atom, an alkyl group having 1 to 20 carbon atoms, and an alkoxy group having 1 to 20 carbon atoms. Base, alkylthio group having 1 to 20 carbon atoms, aryl group having 6 to 40 carbon atoms, heteroaryl group having 3 to 40 carbon atoms, alkenyl group having 2 to 10 carbon atoms, alkynyl group having 2 to 10 carbon atoms, carbon a haloalkyl group having 1 to 10, a trialkylsulfanyl group having 3 to 20 carbon atoms, a trialkyldecylalkyl group having 4 to 20 carbon atoms, a trialkyldecylalkylene group having 5 to 20 carbon atoms, or a divalent group having a carbon number of 5 to 20, a trialkyl decyl alkynyl group substituted, and 2 D each independently represent a group selected from the group consisting of: [Chem. 6] The structure in which the hydrogen atom in the structure may also pass through a hydroxyl group, a halogen atom, a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and an alkylthio group having 1 to 20 carbon atoms. , an alkyl substituted amine having 1 to 20 carbon atoms, an aryl substituted amine having 12 to 40 carbon atoms, a fluorenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 40 carbon atoms, and a carbon number of 3 to 40 Aryl group, carbazolyl group having 12 to 40 carbon atoms, alkenyl group having 2 to 10 carbon atoms, alkynyl group having 2 to 10 carbon atoms, alkoxycarbonyl group having 2 to 10 carbon atoms, alkyl group having 1 to 10 carbon atoms Sulfonyl group, haloalkyl group having 1 to 10 carbon atoms, decylamino group, alkyl guanamine group having 2 to 10 carbon atoms, trialkylsulfonyl group having 3 to 20 carbon atoms, and tridecane having 4 to 20 carbon atoms a group based on an alkylalkyl group, a trialkylsulfonylalkenyl group having 5 to 20 carbon atoms, a trialkylsulfanylalkynyl group having 5 to 20 carbon atoms or a nitro group). An organic light-emitting element characterized in that it has a light-emitting layer containing a compound according to any one of claims 1 to 5 on a substrate. The organic light-emitting element of claim 8, which emits radiation delayed fluorescence. An organic light-emitting element according to claim 8 or 9, which is an organic electroluminescence element.